YY 0719.3-2009Ophthalmic optics - Contact lens care products - Part 3: Microbiological requirements and test methods for products and regimens for hygienic management of contact lenses (English PDF)

4.1 General

The stand-alone test is designed to qualify individual solutions with a suitable level of antimicrobial activity as contact lens disinfection products. The regimen test is designed to qualify individual solutions as part of a contact lens disinfecting regimen. Products meeting the regimen test criteria shall also meet the minimum performance requirements of the stand-alone test. It is fundamental that such products (unopened containers) are capable of meeting the requirements of the test throughout their labelled shelf life.

As described in Figure 1, contact lens care solutions which are designed to possess disinfecting properties shall be tested in the stand-alone test first. If the respective primary criteria are met (see 5.1), the product may be labelled as a contact lens disinfecting product. If the product fails the primary criteria of the stand-alone test, the product must exhibit sufficient antimicrobial activity to meet the secondary criteria of the stand-alone test as listed in 5.2. If these secondary criteria are met, the regimen test shall be performed in order to qualify the product as part of a contact lens disinfecting regimen by meeting the regimen criteria (see 5.3). If the product meets both the secondary criteria of the stand-alone test and the regimen test but fails the primary criteria of the stand-alone test, it shall be labelled as part of a contact lens disinfecting regimen.

The design of contact lens care products for cleaning and contact lens disinfection shall take into consideration the needs of patient compliance and the probability of non-compliance. For example, disinfecting time must be appropriate for contact lens wear.

Note: Use of multiple or mixed microbial challenges can influence the apparent disinfecting activity of a particular product. The evaluation of these variables together with testing against a larger panel of microorganisms and testing of samples from partially used containers may be of value in developing a contact lens care product but are excluded from the scope of this Part.

4.2 Stand-alone test (inoculum challenge test)

The stand-alone test challenges a disinfecting product with a standard inoculum of a representative range of microorganisms and establishes the extent of their viability loss at pre-determined time intervals comparable with those during which the product may be used. The size of the microbial challenge chosen in this test is not intended to be representative of the likely challenge in practice but to provide countable numbers from which estimation of the rate and extent of viability loss can be determined.

In carrying out the test for antimicrobial activity the qualitative and quantitative compositions of the product have to be known at the time of testing by either analytical testing or extrapolation. performance requirements for the stand-alone test may be incorporated into a disinfecting regimen.

In carrying out the antimicrobial activity test, qualitative and quantitative composition of all products used in the test regimen have to be known at the time of testing, either by analytical testing or extrapolation.

Appropriate measures shall be taken to inactivate or remove residual antimicrobial activity during culturing and counting of challenge organism survivors, and the effectiveness of these measures shall be validated. The action of this process during the test shall be demonstrated by the construction of suitable controls.

Note: For problems associated with the use of human-worn lenses, see annex E.

5.1 Stand-alone test: Primary criteria (see also Table 1)

5.1.1 Bacteria

The number of each challenge organism recovered per millilitre shall be reduced by an average value of not less than 99.9 % (3.0 logs) within the minimum recommended soaking period.

Note: The value is determined by taking the average of the log reductions for each challenge organism for the individual lots tested.

5.1.2 Moulds and yeasts

The number of each challenge organism recovered per millilitre shall be reduced by an average value of not less than 90 % (1.0 log) within the minimum recommended soaking period with no increase at not less than four times the minimum recommended soaking period within an experimental error of ± 0.5 logs.

Note: The value is determined by taking the average of the log reductions for each challenge organism for the individual lots tested.

5.2 Stand-alone test: Secondary criteria (see also Table 1)

Products failing to meet the criteria in 5.1.1 or 5.1.2 shall be evaluated by the regimen test procedure described in 6.4, provided the sum of the averages is a minimum of 5.0 log units reduction for the three species of bacteria within the recommended soaking period with a minimum average of 1.0 log unit reduction for any single bacteria. Stasis for the yeast and mould shall be observed for the The following common laboratory equipment is required.

6.1.3.1 Sterile pipettes

6.1.3.2 Swabs

6.1.3.3 Tubes

6.1.3.5 Incubator

6.1.3.8 Centrifuge

6.1.4 Test samples

The product to be tested shall be representative of the product to be marketed.

Aliquots should be taken directly from the final product container immediately prior to testing.

Three lots of samples shall be tested with each prepared inoculum.

6.1.5 Culture maintenance

Maintain the test cultures as recommended by the curator of the appropriate culture collection.

Cultures should be no greater than 5 passes removed from the depository stock (ATCC, NCIB, NCTC, NCPF or other recognized culture depository; see annex A). Each pass is a subculture of the previous pass.

6.2 Preparation of microbial challenge (inoculum)

The preparation of the microbial challenge organisms (inoculum) is common to both the stand-alone test procedure and the regimen test procedure.

For the regimen test procedure, organic soil may be included as part of the inoculum. See annex E for an example.

Culture each test organism on agar slopes under the conditions given in Table 3.

Inoculate the sample tube of a suspension of test organisms sufficient to provide a count of between 1.0 x 10^5 and 1.0 x 10^6 CFU/ml. Ensure that the volume of inoculum does not exceed 1 % of the sample volume. Ensure complete dispersion of the inoculum by adequate mixing.

6.3.2.3 Control specification

If any control value is outside that specified, repeat the procedure as the associated test is invalid.

6.3.3 Test report

The test report shall specify:

a) reference to this Part;

b) the identification of the product:

- name of the product;

- batch number;

- expiry date;

- manufacturer;

- storage conditions;

- active substances(s) and its/their concentration(s) (as available);

If a product passes the primary criteria of the stand-alone test, it may be labelled as a contact lens disinfecting product. If the product only passed the secondary criteria of the stand-alone test, and the regimen test, it shall be labelled as part of a contact lens disinfecting regimen.

6.4 Regimen procedure

6.4.3.6 Incubate bacterial recovery plates at 30 °C to 35 °C. Incubate yeast recovery plates at 20 °C to 25 °C or 30 °C to 35 °C. Incubate mould recovery plates at 20 °C to 25 °C. Incubation times for optimal recovery of bacteria, yeast and moulds shall be determined. Minimum incubation times shall be based on recovery medium control testing (see 6.4.4). Record the number of CFU observed on countable plates. Plates should be observed periodically during incubation to prevent the occurrence of uncountable plates due to overgrowth.

6.4.4 Controls

6.4.4.1 Lens inoculation control

For each microbial species tested, transfer three inoculated lenses to tubes of a suitable diluent (e.g. DPBST). Vortex for 30 s. Serially dilute and plate out appropriate dilutions in triplicate (unless otherwise justified) to permit a count of viable cells present. This count confirms that the number of organisms on the lens at the time of the regimen challenge is adequate. The mean of the counts should be not less than 2 x 10^5 CFU/lens and not greater than 2 x 10^6 CFU/lens.

6.4.4.2 Recovery medium control

Prepare filtration apparatus in triplicate (unless otherwise justified) as described in 6.4.3 with suitable volumes of the neutralizing medium and disinfecting product (see annex B). Let it stand to allow neutralization to be completed. Add 5 CFU to 100 CFU challenge organisms (one organism per filter), filter and cultivate as described in 6.4.3.

6.4.5 Test report

The test report shall include:

a) reference to this Part;

b) the identification of the product:

- name of the product;

- batch number;

B.1 Materials and reagents

B.1.1 Culture media and reagents

B.1.1.1 Diluting fluid, with or without neutralizers. B.1.1.2 Tryptone Soya Agar (TSA) or other suitable media.

B.1.1.3 Dulbecco's Phosphate Buffered Saline without calcium chloride and magnesium chloride (DPBS): 200 mg/l KCl, 200 mg/l KH2PO4, 8000 mg/l NaCl, and 2160 mg/l Na2HPO4 · 7H2O or suitable diluent.

B.1.1.4 Dulbecco's Phosphate Buffered Saline plus 0.05 % polysorbate-80

(DPBST) or suitable diluent.

B.1.1.5 Validated neutralizing agents/media, as required, for example, Dey-

Engley Neutralizing Broth (DEB) and Letheen Broth.

B.1.2 Test equipment

Usual laboratory equipment (such as sterile pipettes, Petri dishes, containers) together with the following.

B.1.2.1 Sterile apparatus for holding the sterile membrane filter and filtrate.

B.1.2.2 Equipment for creating a vacuum or pressure to cause the inoculated test solution to pass through the membrane filter aseptically.

The membrane filter should have a pore size of not greater than 0.45 µm, a diameter of at least 47 mm and should be free of chemicals which could be toxic to microbial cells.

B.2 Test method and results

B.2.1 Moisten the sterile membrane filter in a sterile filter assembly (B.1.2.1) with sterile DPBST (B.1.1.4) or suitable diluent.

B.2.2 Aseptically transfer a measured volume of the inoculated test solution

into 50 ml to 100 ml of sterile DPBST (B.1.1.4) or diluting fluid and thoroughly